Moisture expansion of Ca-rich ceramic body

Calcareous ceramic bodies are typical for historical pottery, e.g. majolica and faience, as well as for contemporary production of ceramic tiles. The amount of the calcium component and the ratio of the other phases together with the firing temperature are responsible for the final properties of the ceramic body. The amount of the calcium component has a fundamental effect on the relative expansion of the ceramic body after firing and also during long-term usage or eventually during storage. The expansion behaviour is mainly associated with the planarity of the final product which is required in the case of large-format tiles. Expansion of the ceramic body is also related to the long-term stability of historical ceramics, especially glazed ceramic objects. In the case of low-fired porous ceramics moisture expansion of the ceramic body occurs due to a humid environment. It is a process of rehydration/rehydroxylation of unstable non-crystalline residues which remain from clay minerals in the ceramic body after firing. This process can be suppressed with a suitable mineralogical composition of calcareous ceramics. The main aim of this work is to study moisture expansion behaviour of calcareous ceramic bodies with a focus on both historical and contemporary ceramics.